JP2023501256A - Compositions and methods of use of fine minerals as catalysts for chemical recycling - Google Patents

Abstract

Embodiments disclosed herein relate to the use of coal-derived fine mineral matter in the chemical recycling of plastics or solid plastic waste. The mineral-based catalysts disclosed herein maximize carbon utilization and production of original quality plastics from recycled or renewable raw materials, while catalytic cracking to reduce plastic pollution in the environment. Benefits gasification and steam reforming processes. Said catalysts can be based on inorganic fine mineral matter, natural ancient mineral mixtures found in coal deposits, and include multiple transition metals such as iron, copper and manganese, as well as calcium, barium, which can act as cocatalysts. Contains magnesium, potassium and sodium. The addition of said catalyst can convert plastics to syngas at the energy rates of the prior art.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This disclosure is a U.S. Provisional Patent Application entitled "Coal-derived fine mineral matter as a catalyst for the chemical recycling of plastics, mixed plastic solid waste and heavy oil feedstocks," filed Oct. 29, 2019. No. 62/927,493 is claimed, the entire text of which is incorporated herein by reference.

FIELD Various embodiments of the present disclosure relate generally to the use of fine mineral matter, such as coal-derived fine mineral matter, in chemical recycling of plastics and/or solid mixed plastic waste, and more specifically, catalytic cracking, gasification and the recycling of waste and heavy oil feedstocks in the presence of mineral-based catalysts that enhance the efficiency of recycling during the process of steam reforming.

The synthetic plastics industry has been one of the great industrial successes of the last 50 years. For example, production of plastics surged from 15 million metric tons in 1964 to 311 million tons in 2014, doubling again over the next two decades, and new uses and applications of plastics being realized year after year. is expected. With the prevalence of plastics in the marketplace, an unintended consequence of this widespread use of plastics is a proportionate and rapid increase in plastic waste and garbage. The amount of plastic that ends up in landfills is estimated to be nearly half of the annual global output, which is over 150 million tons per year. And waste disposal becomes a problem due to the cost and availability of landfills, the toxicity of incineration, and the limited number of cycles that mechanical recycling can support.

Conventional recycling processes have several drawbacks that hinder their scalability and widespread use against the increasing prevalence of the use of plastics in industry. Current recycling processes lack the capacity to handle the diversity of plastic waste, leaving the remaining waste to be landfilled. For wastes that can be recycled and treated, the products made from them are generally of lower quality than the original compounds, resulting in less desirable products and shorter life cycles. For example, this makes landfills more accessible.

According to one embodiment of the present invention, the chemical recycling process is coal-derived and/or mined from natural resources including volcanic basalt, glacial debris deposits, potassium iron silicate and/or coastal sediments, obtaining an amount of catalytic fine mineral matter having a particle size in the range of less than about 50 microns to about 2 microns; or in the presence of water vapor to form a syngas product.

The syngas products may include one or _more of H2, CO, _CH4 , _CO2 , _H2O and inert gases. The catalytic fine mineral matter comprises at least one transition metal selected from the group consisting of Fe, Cu, Mn, Mo, Zn, Co, or combinations thereof, at the following concentrations: Fe 14,000-45,000 ppm; Cu 10-50 ppm, Mn 100-700 ppm, Mo 1-2 ppm, Zn 20-120 ppm, and Co 10-15 ppm, where ppm is nitric acid, hydrochloric acid in a heated digester using the ICP-AES method. and hydrogen peroxide. In some embodiments, the catalytic fine mineral matter comprises alkali and alkaline earth metals Ca, K, Na, Mg, or combinations thereof at the following concentrations: Ca 1,000-18,000 ppm, K 600 4,000 ppm Na, 300-1,500 ppm Na, and 20-8,000 ppm Mg. Said catalytic fine mineral matter can be utilized either as a support material or as a catalyst. The concentration of the catalytic fine mineral matter may range from 0.5 to 8% by volume, or from about 1:5 to about 1:100% by weight catalyst/feed. In some embodiments, particle sizes may range from approximately 5 micrometers to approximately 0.5 micrometers.

Among other things, the molten polymer in the methods disclosed herein is used for steam cracking, gasification of industrial or consumer spent plastic waste, solid mixed plastic waste, or petrochemical heavy oils and alkanes. and can be produced following a catalytic process by a reforming process. Liquefaction precedes gasification, and liquefaction is accomplished through pyrolysis, thermal cracking or steam cracking to convert plastic waste into synthetic heavy oils and condensable gases that can be used in gasifiers and/or steam. Injected into the reformer. The method may also include, following gasification, washing and/or hydrogenation to improve the composition of the syngas product. In some embodiments, the method subjects the synthesis gas to one or more of a KDV process, a Texaco process, or a single or twin column process utilizing fluid bed, fixed bed and entrained flow reactors. be able to.

In some embodiments, said steam cracking may comprise hydrothermal cracking in supercritical water. The reforming process may include catalytic steam reforming of methane to a syngas product. The syngas product may be used as a heat source to promote steam cracking or gasification, or may be used as a gas source to support hydrocracking. Heating can be performed at temperatures ranging from about 200 degrees Celsius to about 500 degrees Celsius. In some embodiments, the method may further comprise energizing the syngas product. Catalytic steam cracking can be batch or continuous flow (slurry type).

This disclosure is more fully understood from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 shows a flow diagram illustrating a method for recycling hydrocarbon plastics according to embodiments disclosed herein. FIG. 2 shows a graph of degradation of stabilized linear low density polyethylene (LLDPE) in air, according to one embodiment of the presently disclosed embodiments. FIG. 3 shows a graph of degradation of modified LLDPE in air, according to one embodiment of the presently disclosed embodiments. FIG. 4 shows a graph of weight change of base LLDPE at various rates, according to one embodiment of the presently disclosed embodiments. FIG. 5 shows a graph of weight change of modified LLDPE at various rates, according to one embodiment of the presently disclosed embodiments.

DETAILED DESCRIPTION Certain illustrative embodiments are described herein to provide an overall understanding of the principles of construction, function, manufacture and use of the systems, devices and methods disclosed within this application. One or more examples of these implementations are illustrated in the accompanying drawings. It will be appreciated by those skilled in the art that the systems, apparatus and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments, and the scope of the present disclosure is defined solely by the claims. you will understand. Features shown or described in connection with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of this disclosure. Furthermore, those skilled in the art will recognize that the ranges disclosed within this application are approximate and merely exemplary. The concentration ranges of transition metals, cocatalysts, and other compounds that make up the catalyst may vary within acceptable values.

In an exemplary embodiment, coal-derived fine mineral matter is utilized in the chemical recycling of plastics or solid plastic waste. The fine mineral matter provides activation energy for pyrolysis of polyethylene (PE) feedstock in the presence of minerals within the scope of embodiments disclosed herein in catalytic cracking, gasification and steam reforming processes. You can work to bring it down. Such technologies can support the mission of reducing plastic pollution in the environment while maximizing carbon utilization and production of pristine quality plastics from recycled or renewable raw materials. For example, the compositions and methods disclosed herein can be used to treat any type of plastic waste (PW), sorted or unsorted, and produce the same quality plastic. . Such technology could allow waste plastics to be converted into raw materials for new plastics, rather than burning them for energy recovery or landfilling. In some embodiments, the fine mineral matter of embodiments disclosed herein can be utilized as a support material for processes discussed in more detail below.

In an exemplary embodiment, chemical recycling can be used to provide unlimited recycling of any plastic material (mixed or sorted), where the focus is on recovering the building blocks of the plastic material. be. Chemical recycling has great potential for heterogeneous and contaminated plastic waste materials where separation is not economically or technically feasible. Chemical recycling can be either closed-loop recycling, where polymers are converted into smaller molecules and then repurposed into the same product they were originally recovered from, or open loop, where those smaller molecules are repurposed into different products. Can be used in loops. Chemical recycling reduces plastic pollution in the environment while transferring the value of the original material to next-generation products, reducing consumption of fossil raw materials (carbon stocks), and reducing GHG emissions associated with fossil raw materials. has the effect of

Chemical recycling pathways can be broadly divided into thermochemical conversions and catalytic conversions, which include steam cracking, pyrolysis, gasification, fluidized catalytic cracking, and hydrocracking, among others. The cracking, gasification and steam reforming processes can be suitably catalyzed and can be carried out in the presence of air or oxygen or steam. Those techniques are of particular interest for polyolefins, polymers which are highly sensitive to oxidative pyrolysis and which account for over 60% of the plastic waste produced. Many other types of polymers can also be very sensitive to catalytic oxidative cracking, gasification and reforming, especially in the presence of steam or supercritical water. Some non-limiting examples of polymers to which the compositions and methods disclosed herein can be applied include acrylics, styrenes, vinyls, polyesters, polyethers, polycarbonates, polyurethanes, polyamides, polyimides, cellulosics, combinations of the above and It may contain copolymers.

Those skilled in the art will recognize that conventional techniques for the production of monomers, mostly olefins, are based on direct thermal cracking of naphthas/alkanes. During cracking, part of the feed is converted to by-products, which are not useful in the direct synthesis of plastics, 40-60% non-olefinic hydrocarbons and 4-25% methane. , up to 10% is benzene. Steam is typically used to reduce the partial pressure of hydrocarbons. Carbon oxides (CO, _CO2 ) and hydrogen can also be produced via steam reforming and gasification in the presence of oxygen-containing molecules in crackers.

More methane is expected to be produced if the feedstock is mixed plastic waste. To achieve 100% carbon recovery, additional processes, such as steam reforming of hydrocarbons to CO and _H2 , and to cover part of the heat demand and recover carbon in the form of _CO2 Combustion of the feed, which also balances the H ₂ /CO ratio of the syngas, can be performed. For combustion processes, _O2 may be produced via electrolysis of water (oxycombustion). Combustion and electrolysis and steam reforming routes are much less fuel dependent than direct steam cracking of feedstock monomers.

In some embodiments, catalytic thermal cracking of plastic waste can be performed in a fluidized bed reactor. For example, in catalytic thermal cracking, the catalyst and absorbent can be introduced in the form of bed materials. In some embodiments, a double fluidized bed (DFB) can be used to separate the heat producing zone (combustion) from the cracking zone. Compared to a single column fluidized bed reactor, the DFB configuration dilutes the cracking products with steam only (and no flue gas) and regenerates the catalyst from carbon deposits in a separate combustion zone. brings additional benefits. The introduction of the catalyst bed material into the fluidized bed reactor can be done during the pyrolysis stage or in a secondary stage of steam reforming of the pyrolysis products.

Steam cracking, as described above, produces a liquefied feedstock, a portion of which can then be sent to a gasification reactor to produce synthesis gas, which is a combination of hydrogen and carbon monoxide. Hydrogenation may also be used to remove sulfur impurities at the end of the gasification process. Syngas produced by gasification can be converted via FTS (Fischer-Tropsch synthesis) or methanol and DME (dimethyl ether) synthesis followed by MTG (methanol to gasoline) or MTO, as discussed in detail below. It can be used in the production of petroleum-like products via conversion (methanol to olefins). Methanol is one of the most produced chemicals in the world because it is used as a reactant to make several commodity chemicals such as formaldehyde, acetic acid, methylamine. Syngas can also be used as a heat source to promote steam cracking or as a gas source to support hydrocracking.

The use of catalytic steam cracking leads to liquid products with lighter compositions and reduces coke formation due to selective low temperature steam reforming (LTSR) of polycyclic aromatic hydrocarbons (coke precursors). can be reduced. Additional hydrogen formed in situ as a result of both the LTSR and water gas reaction can also participate in the upgrade due to saturation of hydrocarbon radicals formed in catalytic steam cracking. To increase the efficiency and effectiveness of catalytic steam cracking, active and selective catalysts that are stable in heavy oil feedstocks and aqueous environments can be used, as described in more detail below. Catalytic steam cracking can be batch or continuous flow with fixed catalyst beds and slurries. In batch mode, dispersed catalysts are currently based on Mo-, Ni- and Fe-compounds. Specifically, the use of Fe-containing dispersed catalysts leads to reduced coking, which is described by Petr Yeletsky et al., “Catalytic steam cracking of heavy oil feedstocks”, Catalyst in Industry, 2018, vol 10, No. 3, pp. 185-201, iron salts promote hydrogen transfer from hydrogen-saturated hydrocarbon molecules to newly formed hydrocarbon radicals and electron transfer between organic compounds due to possible changes in oxidation state. explained by its ability to facilitate. hydrogen transfer of Fe ²⁺ to Fe ³⁺ can lead to saturation of hydrocarbon radicals and the ability of Fe ³⁺ to be reduced to Fe ²⁺ can lead to improved stability of hydrocarbon radicals; This makes it less likely to participate in polycondensation. Heterogeneous supported catalysts, such as ZrO ₂ modified red mud, can be used batchwise. In continuous flow regimes, catalytic steam cracking can be complicated by the hydrodynamic drag of the catalyst bed and rapid deactivation of the catalyst (due to poisoning or coking). To prevent this, slurry-type reactors use dispersed catalysts as disclosed in the present embodiments and, in some embodiments, include the addition of aromatic solvents. Iron compounds such as hematite, which is reduced to magnetite, can be beneficial in this approach (based on their redox chemistry above).

In some embodiments, the compositions of the catalysts disclosed herein can be based on one or more inorganic fine mineral matter, a naturally occurring ancient mineral mixture found in coal deposits, containing multiple transition metals. , such as iron, copper and manganese. Said catalyst may also contain one or more of calcium, barium, magnesium, potassium, sodium, which may act as co-catalysts. One exemplary embodiment of the composition of the catalyst is 30,100 ppm iron, 17,600 ppm calcium, 5,190 magnesium, 2,980 potassium, 1,920 sulfur, 1,190 nitrogen , 253 ppm manganese, 139 ppm phosphorus, 93 ppm zinc, 43 ppm copper, 2 ppm molybdenum. Mineralogical analyzes (XRD, XRF) of the bulk of said fine mineral matter constituting such catalysts are shown in Table 1 below:

_In some embodiments, mineral oxides such as _Al2O3 , BaO, CaO, _{Fe2O3 ,} MgO, _P2O5 , _K2O , _Na2O , _TiO2 , _{MnO2 are} also said fine minerals. may be present in the composition of matter.

Some of the sedimentary clays that make up said fine mineral matter may contain porous structures and water of hydration as well as zeolitic minerals that can act as chemical catalysts. The porous structure of said fine mineral matter ranges from Ca2 ⁺ , Mg2 ⁺ , Na ⁺ , K ⁺ to Fe2 ⁺ , Fe3 ⁺ , Cu ⁺ , Cu2 ⁺ , Mn2 ⁺ and/or Mn3 ⁺ It can accommodate a variety of cations, they are loosely held and readily available to exchange with others and participate in electron transfer reactions.

The bonds in the minerals shown in Table 1 can be either ionic or covalent in character, resulting in various arrangements, symmetries, charges and bonding properties. The ligand field approach is the most applicable because it involves ions or molecules surrounding a central atom or ion and the resulting strength of the ligand field is the controlling factor. Charge transfer processes also occur in the ligand field context and can lead to photochemical oxidation/reduction.

Said fine mineral matter comprises at least one, more preferably at least two transition metals selected from the group consisting of Fe, Cu, Mn, Mo, Zn and/or Co. The concentration of metals and metal salts within said fine mineral matter depends on the analytical method used and is typically X-ray techniques: fluorescence (XRF) and diffraction (XRD) and inductively coupled plasma acid elemental analysis (ICP). - AES). Those transition metals in the fine mineral matter are measured using the ICP-AES method in a thermal digester using nitric acid, hydrochloric acid and hydrogen peroxide and are defined in the ranges shown in Table 2. with concentration:

In some embodiments, the fine mineral matter further comprises a promoter that is an alkali metal/alkaline earth metal. Non-limiting examples of those co-catalysts can include Ca, K, Mg, or combinations thereof to promote oxidative degradation of plastics. The co-catalyst in said fine mineral matter has a concentration defined in the range shown in Table 3. Other alkali/alkaline earth containing minerals with similar fractions of soluble cations can also be used as co-catalysts for oxidative degradation.

Other elements identified by ICP-AES are shown in Table 4:

In some embodiments, the concentration of the catalytic fine mineral matter may depend on the type of reactor. For example, in a continuous fluidized bed reactor, the catalyst-to-feed ratio may range from about 1:5 to about 1:100 wt%, although in some embodiments the range is from about 1:10 to about 1 : 70% by mass. In a batch reactor, the catalyst concentration may range from about 0.5 to about 30 vol.%, and in some embodiments, the range may be from about 0.5 to 8 vol.%. .

Although the fine mineral matter can be separated by foam flotation techniques, or similar processes known to those skilled in the art, and generally have particle sizes ranging from less than about 50 μm to about 2 μm, in some embodiments the particles The size may range from approximately 0.5 to approximately 20 microns. In some embodiments, finer fractions can be used, such as from about 5 microns to about 0.5 microns, or from about 2 microns to about 0.5 microns.

The proposed catalysts enhance the chain scission and oxidative transformation of polymers, the petrochemical heavy oil feedstocks and/or alkanes discussed above, mixed plastic solid wastes or industrial or consumer spent plastics. Increase the yield of CO, _CO2 in thermal catalytic cracking of waste. Transition metal compounds can participate in redox processes in media containing both hydrocarbons and water, i.e. reduction of transition metal oxides with hydrocarbons (oxidative cracking), superheated steam or superheated Reoxidation with water, which may be in the form of a critical fluid, follows. The hydrogen formed in situ during the reoxidation of the reduced compounds can saturate the liquid products and enhance their quality.

The distribution of liquefaction products can be affected by the presence of inherent mineral matter, with raw coal yielding higher yields of benzene and pyridine solubles than deashed coal. Under coal liquefaction conditions, a hydrogen-donating solvent (eg, tetralin) donates its hydrogen to coal-derived free radicals (naphthalene is the primary product of solvent dehydrogenation).

In the embodiments disclosed herein, the free radicals generated from heavy oil or mixed plastic feedstocks are not terminated with hydrogen donating compounds, but rather participate in hydrogen abstraction and high molecular weight hydrocarbons in oxygen-rich environments. promotes further strand unzipping of the

Those skilled in the art will recognize that more severe process conditions (requiring higher temperatures and/or pressures) typically lead to higher proportions of aromatics. In the presence of a catalyst, for example, the severity can be minimized and the composition of the molecules produced can be made more homogeneous, with a lower proportion of aromatics. Complete conversion at low temperatures can simplify subsequent energization, which in some embodiments can be utilized instead of and/or in addition to combustion.

Use of the catalysts disclosed herein can promote partial oxidation, low temperature partial steam reforming and catalytic cracking, significantly increasing the efficiency of cracking and steam reforming/gasification processes. Water can be used in the form of steam, superheated steam or supercritical fluid. Cracking with supercritical water is very efficient in the presence of a catalyst because supercritical water, unlike ordinary water, is nearly non-polar and a good solvent for hydrocarbons. Supercritical water can also disperse high molecular weight hydrocarbons that are not readily soluble or insoluble by forming emulsions, which leads to reduced coke yields and increased liquid product yields. . Supercritical water can increase the efficiency of oxidative cracking by promoting partial oxidation of hydrocarbons and leads to the formation of additional hydrogen.

It will be appreciated that in some embodiments, the disclosed catalysts do not undergo thermal decomposition. Rather, in some embodiments, the catalysts disclosed herein allow steam cracking, reforming, and gasification processes to be performed at reduced process severity conditions, i.e., temperature, pressure, and energy consumption. make it possible. Said catalysts have been shown to lower the activation energy for the cracking of polyolefinic feedstocks when the cracking is carried out in an oxidizing environment, eg under air. The TGA data demonstrate a reduction in the activation energy of pyrolysis of the PE feedstock in the presence of the minerals described, as further described below. For example, in some embodiments the activation energy can be lowered from 43 to 23 kJ/mol using about 2% of said fine mineral matter.

The catalyst can work both in situ and in the reaction after gasification. The former may involve impregnating the catalyst into the feed prior to gasification. It can be added directly to the reactor like a fluidized bed. In the post-gasification reaction, the catalyst is placed in a second reactor (guard bed reactor) downstream of the gasifier to convert the tar and methane formed, which is the operating condition of the gasifier. has the added advantage of being independent of The second reactor can be operated at the optimum temperature for the reforming reaction.

Some non-limiting examples of processes that can be used and/or improved using the catalysts disclosed herein are: (1) KDV process (catalytic pressureless depolymerization process); (2) Texaco process; utilizes fluid bed, fixed bed and entrained flow reactors, and (3) desulfurization of coal sulfur compounds with or without the addition of other catalyst compounds. Additional processes that can benefit from the catalysts disclosed herein are summarized below:

Epoxidation of Olefin Alcohols: The use of vanadium and molybdenum for the epoxidation of simple olefins with alkyl hydroperoxides is known, but has not been utilized for complex molecular syntheses. The use of catalysts based on fine mineral matter may provide a more effective and affordable approach.

Conversion of Syngas to Methanol: The proposed catalyst may also provide further optimization of the catalytic synthesis of methanol from syngas, currently the most common method of industrial production of methanol. Current catalysts for the catalytic conversion of syngas to methanol are based _on ZnO/ _Al2O3 (BASF process) or Cu/ZnO/ _{Al2O3 (} ICI process).

Methanol-to-gasoline (MTG) conversion: A methanol-to _- gasoline synthesis developed by Mobil Oil Corporation catalyzes methanol over a zeolite catalyst _{( NaAlSi2O6.H2O} ) at 350°C and a pressure of about 30 atm. to hydrocarbons. A similar "coal-to-gasoline" process was developed in China by the Jincheng Anthracite Mining Group.

Methanol to Olefins (MTO) Conversion: The MTO process converts methanol to light olefins. Unlike steam cracking, the yield of propylene to ethylene is more flexible, which is a strong advantage over steam cracking. This process currently requires higher temperatures than MTG, but near atmospheric pressure.

In some embodiments, a combination of techniques may also be used, such as a liquefaction stage and an entrained or fixed or fluidized bed gasifier. In the liquefaction stage, plastic waste can be thermally mildly cracked (depolymerized) into heavy synthetic oil and several condensable and non-condensable gas fractions. Non-condensable gases can be reused (along with natural gas) as fuel in liquefaction. The oil and condensable gas can be injected into a gasifier where gasification takes place using oxygen and water vapor. After numerous scrubbing processes, which may include, among other things, the removal of HCl and HF, the clean and dry syngas, consisting primarily of CO and H2, contains minor amounts of _CH4 , _CO2 , _H2O and some _inerts . Produced with gas. Although typical gasification is generally carried out at a temperature range of 1200° C.-1500° C., those skilled in the art will recognize that higher or lower temperatures can be applied to facilitate gasification, which is essentially the same as described above. is the Texaco process. It will be appreciated that the Texaco process requires high temperatures to facilitate conversion.

Said chemical recycling process starts at S1, where a quantity of fine mineral matter is obtained which can be used as a catalyst. The fine mineral matter is separated from coal waste and/or fine size coal using the foam flotation process described above. Said fine mineral matter can also be mined from natural sources such as volcanic basalt, glacial debris deposits, potassium iron silicate and/or other coastal mining deposits. The particle size of the fine mineral matter ranges from less than about 50 μm to about 2 μm. The fine mineral matter contains at least one, more preferably at least two transition metals selected from the group consisting of Fe, Cu, Mn, Mo, Zn, Co, or combinations thereof, and is a non-biodegradable plastic. causes oxidative decomposition of Those transition metals in the fine mineral matter are measured using nitric acid, hydrochloric acid and hydrogen peroxide in a warm digestion tank using the ICP-AES method and are defined in the ranges shown in Table 2 above. has a concentration that

In some embodiments, heating can be performed at temperatures ranging from about 200 degrees Celsius to about 500 degrees Celsius.

The fine mineral matter further contains Ca, K, Mg or a combination thereof to promote oxidative degradation of plastics.

In step S2, the fine mineral matter is contacted with molten polymer or polymer vapor formed during cracking. The contacting with said fine mineral matter can be carried out in the presence of oxygen and/or water vapor at cracking or gasification temperatures, the synthesis gas being rich in H2 and CO with _lesser amounts of _CH4 , _CO2 , Produces with H ₂ O and some inert gases.

In step S3, transition metals in the fine mineral matter catalyze oxidative decomposition. For hydrocarbon-based polymers that are sensitive to radical chain processes, the rate-limiting part of the degradation process is the oxidized segment, commonly referred to as peroxidation. Hydrocarbon polymers differ in their ability to withstand (or undergo) peroxide. Thus, oxidative stability increases from natural rubber (cis-poly(isoprene)) to poly(butylene), polypropylene, polyethylene, and polyvinyl chloride. Among polyethylenes, LDPE and LLDPE are more prone to oxidative degradation than HDPE due to their chemical and morphological properties.

Experimental Data Samples of linear low density polyethylene (LLDPE) and LLDPE modified with the catalysts disclosed herein were analyzed in air from 50°C to 550°C using a TA Instruments Discovery Thermogravimetric Analysis (TGA) analyzer. was tested at rates of 5, 10, 15 and 20°C/min up to °C. The activation energy for decomposition was calculated by the Kissinger method:

where α is the conversion rate, E is the apparent activation energy, kJ/mol, _A is the frequency factor, β is the heating rate, °C/min, and R is the general gas constant. , J/mol °K, T _m is the temperature at the highest decomposition rate, °K, and n is the reaction order. The Kissinger method shows that the product n(1-α) _m ^n-1 is equal to 1 and independent of the heating rate. Rewriting as ln(β×E _a /RT _m ² )=−E _a /RT _m , it can be seen that the dependence of ln(β/Tm ² ) on (1/RT _m ) exhibits a straight line. The apparent activation energy is calculated from the slope and the frequency factor from the intercept of the line on the y-axis.

Figures 2-5 illustrate the effect that catalyst addition can have on LLDPE. As shown in Figure 2, the _Ea for decomposition of the base LLDPE compound in air is 43.4 kJ/mol. The base LLDPE compound also contains 0.2% phenolic primary antioxidant and 0.13% benzotriazole UV absorber. Addition of catalyst to the base LLDPE compound reduces E _a to 20.85 kJ/mol, as shown in FIG. Inclusion of the catalyst thus leads to a reduction of the activation energy E _a of approximately 50% or more in the cracking required in the absence of the catalyst. Those skilled in the art will recognize that "fmm" in the drawings indicates "fine mineral matter." The TGA data for the base LLDPE and modified LLDPE samples used in the _Ea calculations above are shown in FIGS. Degradation is shown at 5 C/min (A), 10 C/min (B), 15 C/min (C) and 20 C/min (D) as shown in Figure 4 for base LLDPE.

For decompositions carried out in nitrogen, the activation energies of base LLDPE and modified LLDPE are 107.83 and 156.44 kJ/mol, respectively. Their values suggest that the fine mineral matter catalyzes oxidation processes and that chemical recycling techniques involving oxidation should be considered. Some non-limiting examples of such techniques can be gasification, thermal cracking or catalytic cracking conducted in the presence of oxygen or other oxidizing environments.

In some embodiments, when testing LDPE compounds with different stabilizing chemistries by TGA, a decrease in activation energy in compounds modified with fine mineral matter has also been demonstrated, with only 0.5 % of said minerals drops from 51.6 to 45.7 kJ/mol.

A summary table of LDPE and LLDPE thermal decomposition TGA data for various materials is shown in Table 5 below.

Those skilled in the art will appreciate further features and advantages of the present disclosure based on the above-described embodiments. Accordingly, the present disclosure is not to be limited to what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited are expressly incorporated herein by reference in their entirety.

Claims (18)

A quantity of catalytic fine mineral matter derived from coal and/or mined from natural sources including volcanic basalt, glacial debris deposits, potassium iron silicate and/or coastal sediments, the amount being from about 2 μm obtaining said catalytic fine mineral matter having a particle size in the range of about 50 μm; and contacting molten polymer or vapor thereof with said catalytic fine mineral matter in the presence of oxygen and/or water vapor at cracking or gasification temperatures. to form a syngas product. _2. The method of claim ₁ , wherein the syngas products comprise one or more of H2, CO, CH4, _CO2 , _H2O and inert gases. The catalytic fine mineral matter contains at least one transition metal selected from the group consisting of Fe, Cu, Mn, Mo, Zn, Co, or combinations thereof, at the following concentrations:
Fe 14,000 to 45,000 ppm,
Cu 10-50ppm,
Mn 100-700ppm,
Mo 1-2 ppm,
20-120 ppm Zn and 10-15 ppm Co
wherein ppm is measured using nitric acid, hydrochloric acid and hydrogen peroxide in a heated digester using the ICP-AES method. The catalytic fine mineral matter contains alkali metals and alkaline earth metals Ca, K, Na, Mg or combinations thereof at the following concentrations:
Ca 1,000 to 18,000 ppm,
K 600 to 4,000 ppm,
Na 300-1,500 ppm, and Mg 20-8,000 ppm
2. The method of claim 1, comprising: 2. The method of claim 1, wherein the concentration of said catalytic fine mineral matter ranges from 0.5 to 8% by volume, or from about 1:5 to about 1:100% by weight catalyst/feed. 2. The method of claim 1, wherein said catalytic fine mineral matter is utilized either as a support material or as a catalyst. The molten polymer is subjected to catalytic processes by steam cracking, gasification and reforming processes of industrial or consumer spent plastic waste, solid mixed plastic waste, or petrochemical heavy oils and alkanes. 2. The method of claim 1, wherein the method is generated by Liquefaction precedes gasification, and liquefaction is accomplished through pyrolysis, thermal cracking or steam cracking to convert plastic waste into synthetic heavy oils and condensable gases that can be used in gasifiers and/or steam. 8. The method of claim 7, injected into the reformer. 8. The method of claim 7, further comprising washing and/or hydrogenation to improve the composition of the syngas product following gasification. 8. The method of claim 7, further comprising subjecting the synthesis gas to one or more of a KDV process, a Texaco process, or a process utilizing a single or twin column fluid bed, fixed bed and entrained flow reactor. described method. 8. The method of claim 7, wherein said steam cracking comprises hydrothermal cracking in supercritical water. 2. The method of claim 1, wherein the reforming process comprises catalytic steam reforming of methane to a syngas product. 2. The method of claim 1, further comprising energizing the syngas product. 2. The method of claim 1, further comprising using the syngas product as a heat source to promote steam cracking or gasification. 2. The method of claim 1, further comprising using the syngas product as a gas source to support hydrocracking. 2. The method of claim 1, wherein the catalytic steam cracking is batch or continuous flow (slurry type). 2. The method of claim 1, wherein the particle size ranges from approximately 5 micrometers to approximately 0.5 micrometers. 15. The method of claim 14, wherein heating is performed at a temperature in the range of about 200 degrees Celsius to about 500 degrees Celsius.

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